Excessive thirst, nausea, weakness in the legs, and bone pain in the spine are all possible indicators of bone marrow cancer, or multiple myeloma. Other signs include weight loss, confusion and recurring infections, according to Mayo Clinic. Some people may not show symptoms immediately.
Bone marrow is the soft tissue located within the bones. Multiple myeloma starts with one abnormal plasma cell from the bone marrow that multiplies and outnumbers healthy blood cells. The body needs healthy red and white blood cells to fight infections, notes Mayo Clinic. The accumulation of abnormal plasma cells can eventually lead to tumors, causing harm to the bones, states Norton Cancer Institute.